Monday, October 4, 2010

DQuest , ORM framework for Qt/Sqlite

I have made a new OSS project for Qt and mobile. It is DQuest , a C++ ORM (Object-relational mapping) for Qt framework. It aims to provide a rapid development environment for application with database access. The database model declaration is very simple , just like other C++/Qt class. It is designed for mobile environment but also useful for desktop and embedded application that do not demand for maximized performance for database.

It is getting more number of application use Sqlite for their data storage. However, writing data model in SQL is complicated . Usually it need to write two set of interface : One for C/C++ and other for Sql. The work load is duplicated, and debug is troublesome.

With DQuest, you can declare a database model using C++ directly. Read / write access can be made through the C++ interface. You won't need to wbrite any SQL to gain the benefit of using Sqlite in your application.

To declare your database model, you need to:
  • Create a class that inherits DQModel
  • Added a DQ_MODEL macro to the class declaration
  • Design your database field by using DQField template type
  • Register your model with DQ_DECLARE_MODEL macro function.

Remarks: DQModel is not QObject based, (QObject is rarely used in DQuest) , therefore you don't need to write setter/getter for each database field.

  • Database model declaration and registration is simple.
    • Declare model in C++/Qt way (p.s QObject is not used)
    • o Support model inheritance
    • o Foreign key - auto load entry
  • Supported operations : create table , drop table , select , delete , insert , query the existence of table , ...
  • Support Sqlite - usable on mobile platform
  • Open source (New BSD license)

    Pending features
    • Multiple database access
      • The software design support to access multiple database , but it is not tested.
    • Multi-threading
      • The software design support multi-threading , but it is not tested.

    • DQuest is still in alpha stage. Use at your own risk.
    • Not all SQL statement and options are implemented , most of them can be added upon on user request. Please join the mailing list.
    • Not implemented operations : create trigger , create index
    • Not supported operations : join select

    DQuest source code is licensed under BSD license. You may use it for open source and closed source application , you just need to obey the requirement of BSD (e.g distribute the license agreement). Moreover, if you can inform us that your application is using DQuest. It can encourage developer to further develop the software.

    Project Page:

    Mailing list:

    API Document


    When I develop the 0.1 version of PenPen Sketchbook , the prototype of drawing interface only spend me few hours , and a working code is completed within two night. However, when I make the sqlite code , it a much longer time to develolop in compare with the drawing function. 60% of time spent on database code totally. I think it is non-sense for such a tiny project. Therefore , that inspired me to develop a C++ ORM for Qt and sqlite.